1. Field of the Invention
This invention relates to surgical instruments and particularly to jaw retractors, also known as mouth gags, for positioning and retaining the jaws in a desired open position during mouth surgery.
2. Description of the Prior Art
This invention is an improvement of the instrument disclosed in U.S Pat. No. 4,024,859 by David H. Slepyan and Jack Nestor entitled Mouth Gag Having Three Dimensional Alveolus Retractor Adjustability.
Whereas the adjustability of the Slepyan and Nestor instrument provides a superior fit and great versatility as compared to the prior Dingman mouth gag, there is a present need for additional surgical exposure accomplished by freedom from supporting elements not actually in use, greater stability in mounting by three point suspension and capability for a balanced, symmetrical two point suspension.
The wide variety of facial configurations presents difficulty encountered by the prior instruments in providing preciseness of fit. This appears to be due to the fixed arcuate shape of the superior support bar and the fixed angle between the latter and its jaw engaging member of the alveolar retractor.
Also, the use of the tongue retractor as the sole lower jaw engaging means has proved to be unreliable, permitting the mouth gag to loosen and shift during surgery and on occasion to be ejected from its properly mounted position. Means for engaging the teeth or gums of the mandible independently of the tongue retractor as well as providing for removably mounting the latter while the mouth gag is being retained in position by coaction between the alveolar and mandibular retractors, as herein provided, will eliminate this problem. The problem of slippage on the teeth by the jaw engaging elements of the alveolar and mandibular retractors is obviated by shaping the contact surfaces for positive engagement between adjacent teeth.